Fab phobia

Overcoming metal cutting challenges, part 2: Don’t fear the exotics – there’s money to be made

by Patrick Medlin, president, Advanced Technology Sales & Service

 

 

 

It shouldn’t come as much of a surprise that most fabricators focus on chasing jobs for sheet metal, plate and aluminum. And to be fair, most stay busy enough to pay the bills and make a pretty decent living as a result. But what if I told you that there are plenty of other uses for that laser cutter sitting out there on the shop floor?

 

Opportunities with lucrative payback are available for fabricators willing to step out of their laser cutting comfort zone. Sounds great, right? So what’s the catch? The stumbling block for many is that they have to be willing to venture into the realm of exotic metals.

 

The mere mention of exotic metals can send chills down the spine of even the most seasoned shop owner or laser operator. Because few are willing to tackle these materials, there are a multitude of untapped opportunities for those equipped to do so. And the best part is that no special equipment or expertise is required. So, if you’ve shied away from exotic metals in the past, now is your chance to get in the game and reap the rewards.

 

 

 Although some fabricators may shy away from cutting exotics, such as copper and brass, the margins for this type of work are high.

 

 

Why exotic metals?

Stainless steel, brass, copper, titanium, armor plate, tool steel, T-1 steel, nickel, super alloys and platinum are just a few of the types of metals that fall into the exotics category. And as it turns out, these and many other exotic materials can be processed with your CO2 laser or fiber laser. We can even add some polymers and plastics to that list.

 

So, why aren’t more fabricators willing to take on such jobs? From my experience there is a simple yet powerful answer: Fear. To get around that sometimes unsubstantiated cutting anxiety, let’s examine the exotic-phobia in more detail and address some of the challenges surrounding laser cutting exotic metals.

 

When we hear the term “exotic metals,” we might be tempted to assume that we’re talking about artistic, delicate or purely aesthetic applications. We typically think of brass or copper in this way. While these metals are certainly prevalent in these circles, other exotic metals are also common throughout industries that are anything but delicate.

 

The truth is that exotic metals are important in applications where quality, durability and tight tolerances are absolutely critical. These metals are a great fit for laser cutting as the parts are often produced more quickly compared to other cutting or machining processes. The laser process creates cleaner edges resulting in less slag and the straight non-tapered edges than one might not get from plasma cutting, for example. This laser cut quality is vital in delivering the extremely high quality, performance and structural integrity that the market expects.

 

Often used in aerospace, medical, and other industries where quality and durability cannot be compromised, titanium is nearly as light as aluminum yet stronger than steel. Because of its strength and weight advantages, titanium is key to these industries. Due to its cost, however, titanium is not used very often in everyday applications.

 

Similar to titanium, super alloys, such as Hastelloy, are desirable because of their strength, ability to tolerate extremely high temperatures and resistance to corrosion. And like titanium, these materials are often used in aerospace applications, such as turbine engines.

 

Likewise, steel armor plate must perform in harsh yet equally demanding applications where failure is not an option. It’s hard to imagine anything more vital than the armor plating encasing a military vehicle. This exotic metal must have a precise fit while maintaining unsurpassed strength and durability – facilitated by the accurate cuts that lasers deliver.

 

Clearly, exotic metals are the material of choice when structural integrity, durability, clean parts, tight tolerances and edge quality are non-negotiable. This helps ensure the best fit for welding operations and overall quality to operate in the manner in which they are intended. Whether for the aesthetics of stainless steel kitchen appliances or the critical performance of a jet engine, exotic metals have a special role, and lasers have a unique role to play in processing these materials.

 

 

The emergence of fiber laser technologies has improved the ability for fabricators to cut and process stainless steel.

 

 

The fear factor

Most fabricators who avoid working with exotic metals do so out of fear. They are afraid of causing damage to their laser machine and intimidated at the thought of ruining expensive metal. Due to the high temperatures required for heating and shaping of parts, exotic metals are very costly to manufacture and process.

 

When processing such expensive material, every part, remnant and scrap must be accounted for as well as material heat and lot numbers. Questions such as, “How many parts did we get out of the sheet? How much scrap did we create and how big are the remnants?” must constantly be addressed.

 

Simply put, fabricators that avoid cutting exotic metals are concerned with losing money. This fear is rooted in a lack of experience and exposure to the process. This is because few lasers, if any, are delivered equipped for cutting exotic metals.

 

While they generally include standard cutting conditions for steel, aluminum, mild steel and even galvanized metal, no laser that I’m aware of comes with preloaded conditions for exotic metals. Consequently, most fabricators have neither the experience nor the resources needed to cut them.

 

 

Most business owners and laser operators overcomplicate the process, as well. When processing exotic metals on a laser, the same variables that most experienced operators are familiar with still apply. Focal position, nozzle centering, proper nozzle selection, nozzle gap, assist gas type and pressure, power, frequency, duty and feed rate all influence the piercing, cutting and cut quality of exotic metals just like they do with their more commonplace counterparts.

 

Do variables like hardness, heat absorption, reflection and vaporization rate more directly influence laser cutting exotic metals? Sure they do; but generally speaking, cutting speed is the variable that is most impacted.

 

The key thing to remember, whether you have a CO2 laser or a fiber laser, is that you have a machine tool that is more than capable of processing nearly all of the aforementioned exotics.

 

My recommendation to customers is for them to request a small sample piece from the customer to do some experimental cutting with. This is a two-fold benefit: It gives you and your laser operators a chance to “test the waters” before you commit to the job and it should yield samples for your potential customer to inspect, test for quality and observe if any heat affects the part from the laser process. Be prepared to return all of the remnants and any unsuccessful first attempts.

 

Opportunities in laser cutting titanium can be found in the aerospace and medical industries, producing a variety of parts such as those that feed into jet engine manufacturing.

 

 

What’s the answer?

The answer is that exotic metals aren’t hard to process – you may just need some advice or assistance to get started and feel comfortable. Here are a few things to consider:

 

  • First off, request the material cutting library or “tech table” from your machine tool vendor for the exotic metals you wish to cut. Most reputable OEMs typically provide such cutting libraries upon request. Some send the program via e-mail where it can be uploaded on to the machine’s controller. The applications department should also be a great source for tips, tricks and things to watch out for in the setup and cutting of the material. Don’t be afraid to ask questions.

 

  • Assist gas is also important. Oxygen and nitrogen are generally the preferred gasses for processing exotic metals. With titanium, however, results are better and higher feed rates are achieved when an argon mix is employed as the assist gas.

 

  • It’s always best to crawl before you walk or run, so I also recommend that first timers start out with the easier and least expensive of the exotic metals. Grade 50 and Grade 80, AR-240 and AR-400 abrasion resistant plate, T-1 alloy, A1 and D2 tool steel and armor plating are very close in laser cutting difficulty as compared to the run-of-the-mill materials that nearly everyone cuts on a daily basis.

 

  • Once you have some successes under your belt from those relatively simple to process exotics, move on to the more expensive and difficult materials: brass, copper, titanium, nickel and platinum. You will also find that due to reflectivity, brass and copper are most easily processed with a fiber laser. A fiber laser can also process these materials in much greater thicknesses than its CO2 counterpart. Only consider laser cutting very thin brass or copper shim stock with a CO2 laser and exercise extreme caution to prevent back reflections.

 

 

When laser cutting titanium, fabricators find better results and higher feed rates when an argon mix is employed as the assist gas.

 

 

The perfect storm

Instead of being afraid to lose money, fabricators should look at exotic metals as an opportunity to increase their margins. Because fewer competitors are vying for this type of work and most customers choose to supply the materials, fabricators can charge a laser cutting premium. With no cash to tie up in the purchase of expensive materials, it’s a perfect storm for those willing to invest the time to learn the process.

 

Don’t be intimidated by the thought of cutting exotic metals. If you’re only processing steel and aluminum with your laser, you’re missing out on a real opportunity. Remember to utilize the applications department where you purchased your laser. They should be happy to answer your questions and help you to more fully optimize your laser capabilities and investment.

 

To read the first installment of Shop Floor Laser’s series on cutting challenging materials, see the article published in the September October issue.

 

Advanced Technology Sales & Service

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